Redox: Oxidation & Reduction | A-level Chemistry | OCR, AQA, Edexcel
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- เผยแพร่เมื่อ 15 ส.ค. 2019
- Redox: Oxidation & Reduction in a Snap!
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The key points covered in this video include:
1. Oxidation and Reduction
2. Electron Transfer
3. Redox Reactions
4. Metals with Acids
Reminder: Oxidation and Reduction
Can be considered in different contexts. Oxygen. Oxidation: Gain of Oxygen. Reduction: Loss of Oxygen. Electrons. Oxidation: Loss of electrons. Reduction: Gain of electrons.
Electron Transfer
This can be summarised as: OIL RIG. Oxidation is loss, Reduction is gain.
Redox Reactions
Reaction where oxidation and reduction occurs. Electrons are transferred. One species loses x electrons, Another species gains x electrons.
Oxidation Numbers
The charge the atom would have if it was composed of ions. Reflects the number of electrons that have been lost/gained. Oxidation: Increase in Oxidation Number. Reduction: Decrease in Oxidation Number.
Redox Reactions: Oxidation Numbers
Changes in oxidation number can reflect whether oxidation or reduction has occured. Oxidation: Increase in oxidation number. Reduction: Decrease in oxidation number.
Redox Reaction: Metals with Acids
Reactive metals react with acids. Metal is oxidised, Hydrogen is reduced to form Hydrogen Gas.
Oxidising and Reducing Agents
In our reactions we have Oxidising and Reducing Agents. They have different roles. Oxidising Agents. Oxidise other things, Are themselves reduced. Reducing Agents. Reduce other things, Are themselves oxidised.
Disproportionation Reactions
These are reactions where the same element is both oxidised and reduced. We can look at the changes in oxidation number to classify reactions. Example: The Decomposition of H2O2. The Oxygen is being both: Oxidised, Reduced
Summary
Oxidation numbers reflect the number of electrons that have been lost/gained
Each atom can be assigned an oxidation number
We use rules to work out oxidation numbers
a. Learn these!
In formulae:
a. In compounds:
i. The sum of the Oxidation Numbers = zero
b. In molecular ions:
i. The sum of the Oxidation Numbers = overall charge on the ion
Roman Numerals are used to represent oxidation states
Transition elements can take multiple oxidation numbers
Oxyanions are -ve ions, containing an oxygen and an element
a. End in -ate
b. Element can take multiple oxidation numbers
Shouldn’t the Hydrogen in N2H4 be 1x4= +4 not -4 to make the Nitrogen -4/2=-2
Omg yes i thought am wrong!!
Was thinking the exact same thing, hydrogen is always +1 (well +4 due to 4 hydrogens) unless if its a metal hydride
16:33 That's what she did though
Very good video.
isnt the second reaction with hydrogen peroxide unbalanced ? to do the disproportionation doesnt it have to be balanced?
Nope
@@inactive2945 At least give a reason for your answer
yea i still don't get it
mood
Doesn’t ammonia form from covalent binds so the hydrogens would gain electrons rather than lose them?
Reuben Constantine Nitrogen is more electronegative than Hydrogen so the covalently shared electrons between Nitrogen and Hydrogen are attracted closer to the nucleus of Nitrogen. In this sense the electrons are further away from hydrogen hence why it has a small positive charge and a oxidation number of +1. You could say that Hydrogen has almost “lost” its covalently bonded electrons to the more electronegative Nitrogen. It is therefore a covalent bond with a lot of ionic character.
"we discussed in our previous video" are frequently mentioned, but where exactly did you discuss it? i watched every videos but didn't see it 😭😭😭
Doesn't the reaction at 6:54 have to be balanced.
Mam aaap bohot aacha padateho
very good and informative vidoo
The snaprevise presenters have been trained to speak this way, but it is extremely annoying. The enunciation is so unnatural I cannot listen to it. Still 100pct better than uplearn though.
cool
bruh this seems not even comparable to cie a level mcqs....
idk though maybe this video just showed very easy questions
aqa boards are rather easier than cambridge
@@rajveen2535 nope lol
6:05
I get the first part then when it gets to the calculations in lost🙄 help me lord
I can't believe that she didn't explain that the oxidation number of oxygen is -1 when its in hydrogen peroxide. Like that left me feeling so confused until I watched this vid th-cam.com/video/zpCy7KwqDO8/w-d-xo.html, which I 100% recommend btw.
should I take a level chemistry
do it
Simple answer no
Depends on what your career plans are
no
@@fatimajatta180 i did it
the amount of mistakes in every video 😭
lmaooo
🙋♂️
Are this instructor is from India
*Is this instructor* (we say teacher round here) from India. Idk probably Indian born or of Indian heritage because of the accent
@USSF - United States Space Force see her face brother.
British mate
there are too many mistakes done by her!!!!
Explains it in the worst way possible